It is generally known that signals, in particular high frequency signals, which are transmitted through transmission lines may suffer from insertion losses. The magnitude of the insertion loss depends on the signal frequency, the transmission line geometry and the material properties. The magnitude of the insertion loss is generally indicated in units of dB loss, 0 dB meaning no loss, −6 dB meaning a loss of a factor two compared to the incident value and −20 dB indicating a loss of a factor ten. A signal transmitted through a transmission line having a first portion with one geometry bordering a second portion with another geometry may suffer significant losses at the border between the first and second portions.
It is further generally known that transmission lines arranged close to each other may exhibit signal cross talk. Also this effect is dependent on the signal frequency and on the geometries and the material properties of the transmission lines concerned.
Obviously both insertion loss and cross talk are undesirable and much research effort is spent designing transmission lines and/or interconnection devices, such as connectors, wherein these effects are reduced or prevented for one or more particular frequencies, preferably over wide frequency ranges.
The most effective methods found to date include widely separating the affected conductors and/or providing additional components for shielding and/or grounding in-between them. However, these solutions counteract the ongoing strive for smaller, less costly devices which preferably also are suited for transmitting a plurality of signals at various high frequencies.
US 2002/0027020 discloses a through-hole structure for connecting a connector to a printed circuit board, the through-hole structure comprising a signal through-hole having a conductive layer therein for supplying a signal to the printed circuit board, power through-holes having a conductive layer therein for supplying power to the printed circuit board, and dielectric constant adjusting portions formed among the signal through-hole and the power through-holes. The through-hole structure is provided to reduce interference and noise in a connector portion of a printed circuit board connected to a high frequency connector, in which the signal through-hole is surrounded by the power through-holes.
US 2006/0255876 discloses a compact via transmission line for a printed circuit board having preferred characteristic impedance and capable of miniaturizing the printed circuit board including a multilayer printed circuit board, and extending the frequency range of a via transmission line mounted on the printed circuit board, and a design method of the same. The transmission line has a central conductor forming an inner conductor layer boundary make up a signal via hole, a plurality of via holes arranged around the central conductor form an outer conductor layer boundary, and a plurality of conductor plates formed of a printed circuit board conductor layer, is further provided with a constitutive parameter adjustment clearance hole between the inner and outer conductor layer boundaries of the compact via transmission line, and electrically isolates to prevent cross-talk of a signal propagating through a signal via hole with other signals in a high-frequency signal band. The disclosed via transmission lines are of the coaxial type, with each signal via hole being surrounded by a shield of ground via holes.
It is an object of the present disclosure to provide improved interconnection devices for high frequency signals, preferably at low voltages (below 5V), which are compatible with increased demands for miniaturisation, low noise levels and manufacturing cost-effectiveness.